Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
TITLE OF THE INVENTION: RADIATION INTENSITY MEASURING APPARATUS
FOR SMALL SEALED RADIATION SOURCE FOR CANCER THERAPY
TECHNICAL FIELD
[0001]
The present invention relates to a radiation intensity
measuring apparatus for small sealed radiation sources for
cancer therapy. More specifically, the present invention
relates to a radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy for measuring
radiation intensity of small sealed radiation sources for use
in small sealed radiation source therapy for prostate cancer.
BACKGROUND ART
[0002]
The small sealed radiation source therapy for prostate
cancer is principally conducted by inserting a radiation source
in which [Iodine-125] which is a radioactive nuclide is
hermetically sealed in a capsule made of titanium (hereinafter,
simply referred to as a radiation source) into prostate. The
radiation source is normally supplied in the state that 5 or
15 radiation sources are packed in a cartridge, and the
cartridge C is provided in the state that it is hermetically
sealed in a container in a sterile condition. The radiation
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sources S are packed in the cartridge C so that their axial
directions are aligned (the axial directions are parallel with
each other) (see Fig. 9).
[0003]
In the small sealed radiation source therapy, on the
assumption that the amount of radioactivity of the radioactive
nuclide hermetically sealed in each radiation source is
identical, the number of radiation sources to be inserted into
prostate and the inserting position thereof are determined
depending on the state of prostate cancer of the individual.
The number of radiation sources to be inserted at one operation
of the small sealed radiation source therapy is about 50 to 150.
However, it is said that the multiple radiation sources
undesirably includes a defective whose amount of radioactivity
is different from the nominal value of the supplier of the
cartridge in the probability of about one in several hundreds
of products, or about two in a hundred of products in products
of bad quality. For example, a radiation source having little
radioactivity, or a radiation source whose amount of
radioactivity is larger than the nominal value can be included.
When such a defective radiation source is used, such problems
arise that an expected therapeutic effect is not obtained due
to shortage of exposed dose, or conversely other tissue is
influenced due to excessive exposed dose. For this reason, the
American Association of Physicists in Medicine (AAPM)
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A
recommends to test at least 10%, and 100%, if possible, of the
radiation sources to be used at each facility.
[0004]
Originally, the radiation intensity of all the radiation
sources should be measured at each facility where the radiation
sources are used, however, in the method for measuring radiation
intensity using an ionization chamber (radiation meter) that
is generally used at present, it is necessary to measure the
amount of radioactivity of the capsule one by one. Since this
has the disadvantages (1) to (7) below, it is actually difficult
to measure the radiation intensity of all of the radiation
sources at each facility.
(1) It is necessary to take out the cartridge that is packaged
in sterile condition from the bag.
(2) It is necessary to take out the radiation source from the
cartridge.
(3) Since the radiation source is measured one by one, very long
time is required.
(4) It is necessary to pack the radiation source taken out from
the cartridge again in the cartridge.
(5) It is necessary to sterilize the cartridge into which the
radiation source is packed again.
(6) It is difficult to avoid exposure to radiation of the
operator's hands and fingers in the operations of (1) to (5).
(7) A special calibrated ionization chamber is required.
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[0005]
In this respect, a radiation intensity measuring
apparatus for each radiation source in the state that the
radiation source is packed in the cartridge has been developed
(Patent Document 1).
Patent Document 1 discloses a technique regarding a
radiation intensity measuring apparatus fora radiation source,
and the measuring apparatus has a receiving part for receiving
a cartridge in which small sealed radiation sources are packed
in its interior, and is also provided with an insertion opening
through which the cartridge is inserted into the receiving part
from outside, and a plurality of openings penetrating the
receiving part and outside.
With such a configuration, a cartridge is inserted into
the receiving part of the measuring apparatus through the
insertion opening, and the measuring apparatus is positioned
on the X-ray film so that the multiple openings are in contact
with the X-ray film. Since the radiation emitted from each
radiation source leaks outside the measuring apparatus through
the corresponding opening, the X-ray film which is in contact
with the measuring apparatus is exposed to the leaking radiation,
and information of the radiation intensity of each radiation
source is recorded on the X-ray film. Therefore, by analyzing
the record on the X-ray film, it is possible to obtain desired
information.
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[0006]
Since the measuring apparatus of Patent Document 1
measures the radiation source packed in the cartridge as it is,
the above problems (2) to (4) can possibly be cleared up, but
the above problems (1) and (5) cannot be solved because
measurement cannot be executed unless the cartridge packaged
in a sterile condition is taken out from the bag.
[0007]
In the measuring apparatus of Patent Document 1, the
problem of decrease in measurement accuracy of radiation
intensity arises for the reason as will be mentioned below
although the above problems (2) to (4) can be solved.
In the case of the measuring apparatus of Patent Document
1, the measuring apparatus exposes the X-ray film to light by
radiation respectively leaking from the multiple openings h.
Therefore, for obtaining the information of the radiation
intensity of each radiation source S, it is necessary to
accurately align the center axes of the multiple radiation
sources S and the center axes of the multiple openings h so that
one radiation source corresponds to each opening h.
However, not all of the radiation sources S packed in the
cartridge C are packed at the same interval, and slight
difference arise in arrangement of the radiation sources S
between individual cartridges C. For example, the radiation
sources S can include a radiation source S having a wire diameter
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. ,
different from the normal wire diameter, and such a radiation
source S can be packed. In this case, as illustrated in Fig.
9 (C) , when the positions of the multiple openings h are formed
at regular intervals in accordance with a normal wire diameter
of the radiation source S (0.8 mm) , the center axis of a certain
radiation source S can be deviated from the center axis of the
opening h. As a result, a radiation source S for which accurate
radiation intensity cannot be measured arises, and measurement
accuracy of the radiation intensity deteriorates.
[0008]
On the other hand, as a technique for solving the problems
(1) to (7) of conventional methods, the technique of Patent
Document 2 has been developed.
Patent Document 2 discloses a radiation intensity
measuring apparatus capable of measuring radiation intensity
of a radiation source packed in a cartridge to be measured in
the state that the cartridge is accommodated in a bag or a
container. This radiation intensity measuring apparatus has
holding means for holding a cartridge accommodated in a bag or
container, and an accommodating part having an accommodation
space into which the cartridge held by the holding means is to
be carried. The accommodating part is provided with a slit that
communicates between the interior of the accommodation space
and outside. For this reason, by carrying the cartridge into
the accommodation space of the accommodating part by the holding
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means, radiation emitted from each radiation source is emitted
outside the accommodating part through the slit. Therefore,
by measuring the intensity of the radiation emitted outside the
accommodating part, it is possible to measure the intensity of
the radiation emitted from the radiation source while the
cartridge is kept accommodated in a bag or container.
In addition, the slit has a width that is smaller than
the axial diameter of the radiation source, so that the holding
means can carry the cartridge into the accommodation space while
keeping the axial direction of the slit and the axial directions
of the radiation sources packed in the cartridge parallel with
each other. Therefore, as the radiation sources packed in the
cartridge are sequentially passed through the position of the
slit, the intensity of radiation emitted outside the
accommodating part through the slit varies with movement of the
radiation sources. Therefore, by measuring the variation in
radiation intensity, it is possible to calculate the intensity
of radiation emitted from each radiation source based on the
variation in the radiation intensity.
PRIOR ART DOCUMENTS
PATENT DOCUMENTS
[0009]
Patent Document 1: Japanese Utility Model Registration
No. 3132529
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a
Patent Document 2: WO 2011-067925 A
SUMMARY OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0010]
As described above, by using the radiation intensity
measuring apparatus of Patent Document 2, it is possible to
measure the radiation intensity of a radiation source while
keeping the cartridge hermetically sealed in a bag or a
container, however, in the apparatus of Patent Document 2, the
operator has to make the cartridge held by the holding means
one by one. In other words, in the radiation intensity
measuring apparatus of Patent Document 2, the holding means
cannot hold multiple cartridges at once. Therefore, in
measuring multiple cartridges, the operator need to repeat the
operation of detaching the cartridge for which measurement has
completed from the holding means, and supplying the holding
means with a new cartridge. Therefore, time and labor are
required, and the operation time extends.
[0011]
In the radiation intensity measuring apparatus of Patent
Document 2, the holding means has to hold the radiation source
held by the cartridge in a predetermined posture (the state that
the axial direction of the radiation source is parallel with
the axial direction of the slit). As a result, in measuring
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the radiation intensity of the radiation source S for radiation
sources held by a container or cartridge having different shape,
the holding means adapted to the shape of the container or
cartridge is required. For measuring radiation intensity of
a radiation source held by a container or cartridge having a
different shape, it is necessary to change the holding means.
In the radiation intensity measuring apparatus of Patent
Document 2, since the holding means is configured to carry the
cartridge into the accommodation space of the accommodating
part, time and labor are required for changing operation of the
holding means. Therefore, in the radiation intensity
measuring apparatus of Patent Document 2, it is difficult to
rapidly correspond to the change in cartridge to be measured.
[0012]
Further, in the radiation intensity measuring apparatus
of Patent Document 2, the holding means that holds the cartridge
is moved. Since the cartridge has a certain degree of size,
the holding means inevitably has a certain degree of size.
Accordingly, the size of the mechanism for moving the holding
means increases, and it is difficult to downsize the apparatus.
[0013]
In light of the above circumstances, it is an object of
the present invention to provide a radiation intensity
measuring apparatus for small sealed radiation sources for
cancer therapy capable of measuring multiple cartridges
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efficiently as well as quickly, and capable of downsizing the
apparatus.
MEANS FOR SOLVING THE PROBLEMS
[0014]
A radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
first aspect of the invention is a radiation intensity measuring
apparatus for multiple radiation sources, in which multiple
radiation sources are held in a cartridge, and radiation
intensity of the multiple radiation sources is measured while
they are held by the cartridge, the apparatus includes: holding
means capable of holding the cartridge; radiation intensity
measuring means for measuring intensity of radiation emitted
from the multiple radiation sources packed in the cartridge in
the state that the cartridge is held by the holding means; and
moving means for moving the radiation intensity measuring means
toward or away from the holding means, the holding means
includes: a radiation emitting part capable of emitting
radiation emitted from the multiple radiation sources outside
the holding means in the state that the cartridge is held by
the holding means, the radiation intensity measuring means
includes: a sensor for measuring radiation intensity, and a
shielding member provided for restricting radiation irradiated
to the sensor; the shielding member is disposed to be positioned
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between the radiation emitting part of the holding means and
the sensor in a measurement state where the radiation intensity
measuring means is moved toward the radiation emitting part of
the holding means, the shielding member is formed with a slit
that penetrates between a face positioned on the side of the
radiation emitting part of the holding means and a face
positioned on the side of the sensor in the measurement state,
the slit is formed so that width thereof is smaller than a wire
diameter of the radiation source, the moving means is configured
to be able to relatively move the radiation intensity measuring
means along the direction orthogonal to an axial direction of
each radiation source held by the cartridge in the measurement
state.
The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
second aspect of the invention is characterized in that the
moving means is controlled to move the radiation intensity
measuring means also in an axial direction of the radiation
source in relatively moving the radiation intensity measuring
means along the direction orthogonal to the axial direction of
the radiation source held by the cartridge in the measurement
state in the first aspect of the invention.
The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
third aspect of the invention is characterized in that the
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cartridge has a seed holding part in which the multiple
radiation sources are packed so that the axial directions of
the plural radiation sources are substantially parallel with
each other, and the moving means is configured to be able to
relatively move the radiation intensity measuring means along
the direction in which the multiple radiation sources are
arranged in the seed holding part of the cartridge in the
measurement state in the first or second aspect of the
invention.
The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
fourth aspect of the invention is characterized in that the
holding means is configured to be able to hold multiple
cartridges, and has a plurality of radiation emitting parts
respectively corresponding to positions of the seed holding
parts of the multiple cartridges in the state that the multiple
cartridges are held in the first, second or third aspect of the
invention.
The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
fifth aspect of the invention is characterized in that the
moving means is able to position the radiation intensity
measuring means to give a state that an axial direction of the
radiation source to be measured in the measurement state and
an axial direction of the slit of the shielding member are
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parallel with each other, and move the radiation intensity
measuring means while keeping the state in the first, second,
third or fourth aspect of the invention.
The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
sixth aspect of the invention is characterized in that the
holding means has an opposed face situated on the side of the
radiation intensity measuring means in the measurement state,
and a supply face situated on the opposite side of the opposed
face, the supply face is formed with an accommodation groove
recessed from the supply face to the opposed face, for
accommodating the cartridge, the accommodation groove is formed
so that the axial directions of the multiple radiation sources
are parallel with the opposed face when the cartridge is
accommodated in the accommodation groove, and the radiation
emitting part is formed at positions corresponding to the
positions where the multiple radiation sources are positioned
when the cartridge is accommodated in the accommodation groove
in any one of the first to fifth aspects of the invention.
The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
seventh aspect of the invention is characterized in that the
radiation emitting part is a through hole penetrating between
an inner bottom face of the accommodation groove and the opposed
face in the sixth aspect of the invention.
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The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
eighth aspect of the invention is characterized in that the
apparatus further includes a base in which the moving means is
provided, and the holding means includes: a holding plate for
holding the cartridge, and a frame part for positioning the
holding plate apart from the base, the radiation emitting part
is provided at a position where radiation from the radiation
source can be emitted into a space between the holding plate
and the base in the holding plate, and the radiation intensity
measuring means is disposed to be able to move in the space
between the holding plate and the base by the moving means in
any one of the first to seventh aspects of the invention.
The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
ninth aspect of the invention is characterized in that the
holding plate has a flat reference face on the side of the base,
and holds the cartridge so that the axial directions of the
multiple radiation sources are parallel with the reference face,
the radiation intensity measuring means is provided so that a
shielding face situated on the side of the radiation emitting
part of the holding means in the shielding member and the
reference face are parallel with each other, and the moving
means moves the radiation intensity measuring means while
keeping the shielding face and the reference face parallel with
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each other in the eighth aspect of the invention.
The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
tenth aspect of the invention is characterized in that the
holding plate is provided detachably from the frame part in the
eighth or ninth aspect of the invention.
The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy according to the
eleventh aspect of the invention is characterized in that the
apparatus further includes a calibration part provided with a
reference radiation source which is a reference of intensity
of radiation emitted from the radiation source, and the
shielding member is movable between a measurement position
where a detecting part of the sensor is covered, and a
calibration position where the detecting part of the sensor is
exposed, and the calibration part is provided with a shielding
member moving mechanism for moving the shielding member to the
calibration position while moving the radiation intensity
measuring means to the position of the reference radiation
source of the calibration part by the moving means in any one
of the first to tenth aspect of the invention.
EFFECT OF THE INVENTION
[0015]
According to the first aspect of the invention, by making
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the holding means hold the cartridge, and moving the radiation
intensity measuring means toward or away from the holding means
by the moving means, it is possible to measure the intensity
of the radiation emitted from the radiation emitting parts by
the sensor of the radiation intensity measuring means. In
addition, in the measurement state, the shielding member having
the slit is disposed between the radiation emitting part and
the sensor. Therefore, by relatively moving the radiation
intensity measuring means along the direction orthogonal to the
axial direction of the radiation source by the moving means,
it is possible to measure the intensity of the radiation emitted
from the radiation source as a variation in the radiation
intensity.
According to the second aspect of the invention, by moving
the radiation intensity measuring means also in the axial
direction of the radiation source, it is possible to measure
the radiation intensity of the radiation source based on the
measurement result at the position where the radiation
intensity can be measured maximally in the axial direction of
the radiation source. Therefore, it is possible to improve the
estimation accuracy of the intensity of the radiation of the
radiation source.
According to the third aspect of the invention, by moving
the radiation intensity measuring means along the direction in
which the multiple radiation sources are arranged, it is
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possible to sequentially measure the radiation intensity of the
multiple radiation sources. Therefore, it is possible to
reduce the time required for measuring the radiation intensity
of the multiple radiation sources.
According to the fourth aspect of the invention, since
the holding means holds the multiple cartridges, it is possible
to sequentially measure the radiation intensity of the
radiation sources packed in the multiple cartridges merely by
moving the radiation intensity measuring means by the moving
means. As a result, it is not necessary to replace the measured
cartridge by the cartridge to be measured next every time each
cartridge is measured, so that it is possible to reduce the
operation time for the operation of measuring the radiation
intensity of the radiation sources packed in the multiple
cartridges.
According to the fifth aspect of the invention, since the
radiation intensity measuring means is moved by the moving means
while the axial directions of the multiple radiation sources
are kept parallel with the axial direction of the slit of the
shielding member, it is possible to accurately measure the
intensity of the radiation emitted from each radiation source.
According to the sixth aspect of the invention, only by
accommodating the cartridge in the accommodation groove, the
multiple radiation sources are positioned so that their axial
directions are parallel with the opposed face. As a result,
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it is not necessary to conduct the operation of registering the
axial directions of the radiation sources to the opposed face
by adjusting the posture of the cartridge in accommodating the
cartridge in the accommodation groove, so that it is possible
to reduce the preparation time for measuring the radiation
intensity. Since it is only required to accommodate the
cartridge in the accommodation groove, the time during which
the operator touches the cartridge is reduced, and hence the
exposed dose of the operator also can be reduced.
According to the seventh aspect of the invention, since
the radiation emitting part is a through hole, it is possible
to simplify the structure of the holding means. In addition,
since attenuation of radiation between the multiple radiation
sources and the sensor can be reduced, it is possible to
accurately grasp the intensity of the radiation emitted from
the radiation source.
According to the eighth aspect of the invention, since
radiation is emitted from the radiation source into the space
between the holding plate and the base, it is possible to reduce
the amount of radiation leaking outside from the apparatus.
According to the ninth aspect of the invention, it is
possible to make the positional relation between the radiation
source in the seed holding part of the multiple cartridges held
by the holding plate, and the sensor of the radiation intensity
measuring means substantially identical in any cartridge. As
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a result, it is possible to prevent occurrence of difference
in measuring result of radiation intensity between different
cartridges.
According to the tenth aspect of the invention, since the
holding plate is provided detachably from the main body, it
becomes possible to measure a cartridge of different shape only
by changing the holding plate. Therefore, it is possible to
readily change the cartridge to be measured. In addition, if
the cartridge is provided in the state of being accommodated
in the holding plate, there is no need to set the cartridge in
the holding plate. As a result, preparation for measurement
of radiation intensity can be conducted in short time, and the
operator hardly needs to touch the cartridge, and thus the
exposed dose of the operator can be further reduced.
According to the eleventh aspect of the invention, by
moving the radiation intensity measuring means to the position
of the reference radiation source of the calibration part by
the moving means, it is possible to conduct calibration of the
sensor automatically. In addition, by conducting calibration
of the sensor every time before measuring each cartridge, it
is possible to keep the accuracy of estimating the radioactivity
of the radiation source of each cartridge high.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016]
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Fig. 1 is a schematic plan view of a radiation intensity
measuring apparatus 1 for small sealed radiation sources for
cancer therapy according to the present embodiment.
Fig. 2 is a schematic plan view of a radiation intensity
measuring apparatus 1 for small sealed radiation sources for
cancer therapy according to one embodiment, in the state that
a holding plate 12 is detached.
Fig. 3 is a sectional arrow view along the line 111-111
in Fig. 1.
Fig. 4 is an arrow view of an essential part along the
line IV in Fig. 3.
Fig. 5 is an arrow view along the line V in Fig. 3.
Fig. 6(A) is a schematic explanatory view in the state
that a shielding member 32 is close to a calibration part 40,
and Fig. 6(B) is a schematic illustrative view in the state that
the shielding member 32 is positioned at a calibration position
by a shielding member moving mechanism 45 of the calibration
part 40.
Figs. 7 are schematic explanatory views illustrating
areas of radiation emitted from respective radiation emitting
parts 12f, and Fig. 7(A) is a section view in the x direction
of Fig. 1, and Fig. 7(B) is a section view in the y direction
of Fig. 1.
Figs. 8 are explanatory views of a holding plate 12 alone,
in which Fig. 8(A) is a plan view, and Fig. 8(B) is a section
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view along the line B-B.
Fig. 9(A) is a schematic explanatory view of a cartridge
C, and Figs. 9(B) and 9(C) are schematic explanatory views of
a slit h part in the state that cartridge C is inserted into
a measuring apparatus of Patent Document 1.
Figs. 10 are schematic explanatory views of a plastic case
PK accommodating the cartridge C, in which Fig. 10(A) is a
lateral view, Fig. 10(B) is a plan view, and Fig. 10(C) is a
view taken in the direction of the arrow C in Fig. 10(A).
Figs. 11 are schematic explanatory views of a rectangular
cartridge C2, in which Fig. 11(A) is a perspective view, Fig.
11(B) is a plan view, and Fig. 11(C) is a lateral view.
Figs. 12 are schematic explanatory views of a holding
plate 12B for the rectangular cartridge C2, in which Fig. 12(A)
is a plan view in the state that the rectangular cartridge C2
is accommodated, Fig. 12(B) is a plan view of the holding plate
12B alone, and Fig. 12(C) is a back side view of the holding
plate 12B alone.
Fig. 13 are schematic explanatory views of a shaft-shaped
cartridge C3, in which Fig. 13(A) is a perspective view, Fig.
13(B) is a lateral view, and Fig. 13(C) is a plan view.
Figs. 14 are schematic explanatory views of a holding
plate 12C for the shaft-shaped cartridge C3, in which Fig. 14(A)
is a plan view in the state that the shaft-shaped cartridge C3
is accommodated, Fig. 14(B) is a plan view of the holding plate
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120 alone, and Fig. 14(C) is a back side view of the holding
plate 120 alone.
Fig. 15(A) is a schematic explanatory view in the state
that radiation sources S are accommodated at axially displaced
positions in a seed cartridge SC, Fig. 15(B) is a schematic
explanatory view when the radiation intensity is measured by
moving a radiation intensity measuring means 30 in the state
of (A), and Fig. 15(0) is a view exemplarily showing the
measurement results of the radiation sources a to c in (A) when
the radiation intensity is measured by the method of (B). The
moving amount of the radiation intensity measuring means 30 in
(B) is illustrated in the state that it is extremely moved for
easy understanding of the operation, and is not necessarily
coincident with the actual movement.
MODE FOR CARRYING OUT THE INVENTION
[0017]
Next, embodiments of the present invention will be
described with reference to the attached drawings.
A radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy is used for
measuring an amount of radioactivity of a radioactive nuclide
hermetically sealed in a radiation source for use in a small
sealed radiation source therapy for prostate cancer, and is able
to measure the intensity of the radiation emitted from the
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radiation sources packed in the cartridge.
[0018]
(Description of radiation source S and cartridge C)
As described above, the radiation intensity measuring
apparatus for small sealed radiation sources for cancer therapy
according to the present embodiment (hereinafter, referred to
as a radiation intensity measuring apparatus 1 of the present
embodiment) measures the intensity of the radiation emitted
from radiation sources S packed in the cartridge. Before
describing the radiation intensity measuring apparatus, the
radiation sources S which are objects to be measured, and the
cartridge C in which the radiation sources S are packed will
be described.
[0019]
(Regarding radiation source S)
The radiation source S is prepared by hermetically
sealing [Iodine-125] which is a radioactive nuclide in a capsule
made of titanium, and has such a shape that the axial length
is longer than the wire diameter. The radiation source S that
is commonly used has a wire diameter ranging from 0.80 to 0.95
mm and an axial length ranging from 4.50 to 4.55 mm, and the
wire diameter and the axial length have slight variations.
[0020]
(Regarding cartridge C)
Next, the cartridge C that holds the radiation sources
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S will be described.
The cartridge C is generally used for small sealed
radiation source therapy for prostate cancer, and normally used
in the state that it holds multiple radiation sources S. As
the shape of the cartridge C, various shapes are used. For
example, the one having a shape as illustrated in Fig. 9(A),
the one having a shape as illustrated in Fig. 11, and the one
having a shape as illustrated in Fig. 13 are used, however, the
cartridge C for measuring the radiation intensity of the
radiation sources S in the radiation intensity measuring
apparatus 1 of the present embodiment is not particularly
limited.
[0021]
First, the cartridge C having the shape as illustrated
in Fig. 9(A) will be described.
As illustrated in Fig. 9(A), the cartridge C includes a
magazine M having a substantially cylindrical shape, a seed
cartridge SC in which multiple radiation sources S are packed,
provided at one of axial ends of the magazine M, and a pusher
P in the form of a rod penetrating the center axis of the magazine
M. A tip end of the pusher P reaches the space where the
radiation sources S are packed in the seed cartridge SC, and
has a function of holding the multiple radiation sources S
packed in the seed cartridge SC in the state that they are in
close contact with each other with the axial directions thereof
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being parallel with each other.
[0022]
The aforementioned seed cartridge SC is located on the
.
center axis of the magazine M. The seed cartridge SC is a
plate-like member (about 3.1 mm in thickness) having a tip end
face formed into a flat plane orthogonal to the center axis of
the magazine M, and a surface formed into a plane parallel with
the center axis of the magazine M. The seed cartridge SC has
the aforementioned space in which the radiation source S is
packed. This space is formed so that the height of its section
is substantially the same with the wire diameter of the
radiation source S, and the width of its section is
substantially the same with the length of the radiation source
S. The space is formed in such a manner that the axial
directions of the multiple radiation sources S are parallel with
the tip end face and the surface of the seed cartridge SC, when
the multiple radiation sources S are held by the aforementioned
pusher P in such a state that they are in close contact with
each other and their axial directions are parallel with each
other.
[0023]
The number of radiation sources S packed in the space of
the seed cartridge SC is not particularly limited, but it is
generally five or fifteen.
Regarding "magazine M having a substantially cylindrical
CA 02886802 2015-03-30
. .
shape" used in the above description, a substantially
cylindrical shape is conceptual wording including the shapes
such as a hexagon or an octagon generally employed in a magazine
M of a cartridge C.
[0024]
(Regarding other cartridge)
Next, the cartridge having the shape illustrated in Fig.
11 (rectangular cartridge C2) will be described.
[0025]
As illustrated in Fig. 12, the rectangular cartridge 02
has a substantially rectangular main body M whose opposing
surfaces are formed into flat planes that are parallel with each
other. The main body M has a hollow space capable of
accommodating the radiation sources S therein, and one of its
end parts (left end in Figs. 12(B) and 12 (C) ) forms the seed
cartridge SC in which the multiple radiation sources S are
packed.
[0026]
The main body M of the rectangular cartridge C2 is
provided with the pusher P having the same function as the
aforementioned cartridge C (see Fig. 9 (A) ) . The pusher P is
a rod-like member that penetrates the center axis of the main
body M, and is provided to be able to push the multiple radiation
sources S in the main body M toward one of the end parts of the
main body M.
26
CA 02886802 2015-03-30
[0027]
In the main body M of the rectangular cartridge C2, the
internal space of the seed cartridge SC is formed so that the
height of the section is substantially identical to the wire
diameter of the radiation source S, and the width of the section
is substantially identical to the length of the radiation source
S. The inner surface of the interior of the seed cartridge SC
is formed to be substantially parallel with the surface of the
seed cartridge SC (in other words, the surface of the main body
M).
[0028]
The multiple radiation sources S are accommodated in the
internal space of the main body M of the rectangular cartridge
C2, and the multiple radiation sources S are pushed by the
aforementioned pusher P. As a result, the multiple radiation
sources S are held in the seed cartridge SC in the state that
their axial directions are parallel with each other and they
are in close contact with each other. Also, the multiple
radiation sources S are packed in the seed cartridge SC in such
a manner that their axial directions are parallel with the
surface of the seed cartridge SC.
[0029]
Also in the rectangular cartridge C2, the number of
radiation sources S packed in the space of the seed cartridge
SC is not particularly limited, but it is generally five or
27
CA 02886802 2015-03-30
. .
' .
fifteen as is the case with the cartridge C.
[0030]
(Regarding still another cartridge)
Next, the cartridge having the shape illustrated in Fig.
13 (shaft-shaped cartridge C3) will be described.
[0031]
As illustrated in Fig. 13, unlike the cartridge C and the
rectangular cartridge 02 as described above, the shaft-shaped
cartridge 03 holds a pair of radiation sources S while
connecting them so that their axial directions are
substantially coaxial.
[0032]
In the shaft-shaped cartridge 03, its main body M is
formed into a substantially cylindrical shape. The
shaft-shaped cartridge 03 is formed with a flat plane Na that
is parallel with the axial direction of the main body M, on the
side face of the main body M. The flat plane Ma is formed with
a groove Mg along the axial direction of the main body M, and
in the groove Mg, a strap member SB accommodating the radiation
sources S therein is accommodated. The strap member SB
accommodates the radiation sources S at constant intervals
along its axial direction. And, the radiation sources S are
arranged so that their axial directions coincide with the axial
direction of the strap member SB.
[0033]
28
CA 02886802 2015-03-30
. .
In the shaft-shaped cartridge C3 having the structure as
described above, by disposing the strap member SB in the groove
Mg of the main body M, it is possible to hold the radiation
sources S in the state that they are arranged along the axial
direction of the main body M at constant intervals.
[0034]
Preferably, the strap member SB is formed to have a
thickness that will not fall out of the groove Mg when it is
arranged in the groove Mg with the radiation sources S
accommodated therein. The configuration of fixing the strap
member SB in the groove Mg, or in other words, the configuration
of preventing the strap member SB from falling out of the groove
Mg is not particularly limited. For example, from the view
point of preventing the strap member SB from falling out of the
groove Mg, a structure that allows hooking of both end parts
of the strap member SB may be provided in end parts of the groove
Mg of the main body M. Concretely, a projection or the like
may be provided in end parts of the groove Mg of the main body
M to fix the strap member SB in the groove Mg. In particular,
by forming end parts in the groove Mg to have an acute angle,
it is possible to make the strap member SB difficult to fall
out of the groove Mg (see Fig. 13) .
[0035]
(Regarding a further other cartridge)
Also the one connecting a pair of radiation sources S so
29
CA 02886802 2015-03-30
=
that their axial directions are substantially coaxial, and
retaining the same may be used as a cartridge.
[0036]
For example, as the cartridge, a substantially
cylindrical cartridge having an insertion hole through which
the radiation source S is inserted in both end parts (or in either
end part) is used. In this case, the insertion hole is formed
so that its inner diameter is slightly smaller than the diameter
of the radiation source S. That is, the insertion hole of the
cartridge is formed to have a size capable of holding the
radiation source S so that the radiation source Swill not fall
off when the radiation source S is inserted into the insertion
hole.
[0037]
As a result, by attaching the multiple radiation sources
S to the insertion hole of the cartridge, it is possible to
connect the multiple radiation sources S via the cartridge.
[0038]
The number of radiation sources S connected by the
cartridge (connecting cartridge) is not particularly limited.
Since the cartridge having such a structure is normally placed
in a living body together with the radiation sources S, an
appropriate number of radiation sources S may be connected
depending on, for example, the place where the radiation sources
S are placed together with the cartridge.
CA 02886802 2015-03-30
. .
. .
[0039]
(Regarding package of cartridge C)
The cartridge C, the rectangular cartridge C2, the
shaft-shaped cartridge C3, the connecting cartridge and so on
described above (hereinafter, simply referred to as cartridge
C) can be provided while the multiple cartridges C are packaged
in a container such as a can in hermetically sealed and
sterilized condition. In this case, the cartridge C is taken
out from the container, and the cartridge C is held in the holding
means as will be described later, and the radiation intensity
of the radiation sources S packed in the cartridge C is measured.
[0040]
On the other hand, the cartridge C can be provided while
it is individually packaged in a bag or container in
hermetically sealed and sterilized condition. For example,
the cartridge C may be provided while it is hermetically sealed
in a bag made up of a paper sheet (backing paper) of about 0.18
mm in thickness, and a synthetic resin sheet (cover sheet) of
about 0.05 mm in thickness. Concretely, the peripheral parts
of the sheets are bonded together with the cartridge C
sandwiched therebetween to hermetically seal the cartridge C
in the bag, and thus the cartridge C that is hermetically sealed
in the bag can be provided.
[0041]
In the case where the cartridge C is provided while it
31
CA 02886802 2015-03-30
. .
' .
is hermetically sealed in a bag or a container individually,
the cartridge C may be taken out from the bag or the container
and the radiation intensity of the radiation sources S may be
measured in the same manner as in the case where the multiple
cartridges C are provided while they are hermetically sealed
in the container in sterilized condition. However, in the case
where the cartridge C is provided while it is hermetically
sealed in a bag or a container individually, it is possible to
measure the radiation intensity of the radiation source S while
keeping the cartridge C hermetically sealed in the bag or the
container. As will be described later, by making the shape of
the holding means (accommodation groove 12g of holding plate
12) coincident with the shape of the bag or the container, it
is possible to measure the cartridge C while keeping it
hermetically sealed in the bag or the container.
[0042]
For example, when the cartridge C has the shape as
illustrated in Fig. 9(A), it becomes possible to measure the
radiation intensity of the radiation sources S while keeping
the cartridge C accommodated in the container by the radiation
intensity measuring apparatus 1 of the present invention by
employing the following shape.
[0043]
In Fig. 10, the reference symbol PK denotes a plastic case
that accommodates the cartridge C.
32
CA 02886802 2015-03-30
. ,
' .
As shown in Fig. 10, the plastic case PK is made up of
a plastic accommodation case PC having a recessed part
(hereinafter, referred to as a recess part d) , and a cover sheet
ST provided to close the opening of the recess part of the
accommodation case PC.
[0044]
As shown in Fig. 10, the accommodation case PC is a member
formed of a plastic material having a certain degree of strength.
The accommodation case PC includes the recess part d
accommodating the cartridge C therein, and a flange part f
provided in the periphery of the opening of the recess part d.
[0045]
The recess part d is so formed that when the cartridge
C is accommodated therein, the axial direction of the cartridge
C substantially coincides with the axial direction of the recess
part d, and motion of the cartridge C inside the same can be
limited.
[0046]
Concretely, in the center part of the recess part d, a
magazine accommodating part db for accommodating the magazine
M of the cartridge C is provided. The magazine accommodating
part db has a depth and a width that are slightly larger than
the diameter of the magazine M, and has a length that is slightly
larger than the axial length of the magazine M.
The magazine accommodating part db has a shape capable
33
CA 02886802 2015-03-30
of holding the magazine M so that the axial direction of the
magazine M accommodated therein substantially coincides with
the axial direction of the magazine accommodating part db.
[0047]
On the lateral side of the magazine accommodating part
db, a seed cartridge accommodating part da which is a space
communicating with the magazine accommodating part db is
provided. The seed cartridge accommodating part da is formed
to accommodate the seed cartridge SC when the magazine M of the
cartridge C is accommodated in the magazine accommodating part
db.
The seed cartridge accommodating part da is formed so that
when the seed cartridge SC is accommodated therein, the axial
direction of the seed cartridge accommodating part da and the
axial directions of the multiple radiation sources S in the seed
cartridge SC are substantially orthogonal to each other.
The seed cartridge accommodating part da is formed so that
the bottom of its recess (top face in Fig. 10) is a flat plane,
and has a depth Op that is roughly equivalent to the sum of the
radius of the magazine M and the thickness of the seed cartridge
SC.
The width of the seed cartridge accommodating part da is
slightly wider than the width of the seed cartridge SC.
Concretely, it is formed to be wider than the width of the seed
cartridge SC by about several millimeters.
34
CA 02886802 2015-03-30
*
[0048]
The recess part d also has a recess substantially
identical to the seed cartridge accommodating part da on the
opposite side of the seed cartridge accommodating part da with
respect to the magazine accommodating part db.
[0049]
The flange part f is provided on the periphery of the
opening of the recess part d, and has the surface (top face and
bottom face in Fig. 10) parallel with the bottom face of the
seed cartridge accommodating part da.
[0050]
Since the recess part d and the flange part f are formed
in the manner as described above, when the cartridge C is
accommodated in the recess part d of the accommodation case PC,
the axial direction of the cartridge C substantially coincides
with the axial direction of the recess part d. In addition,
the cartridge C is positioned so that the surface of the seed
cartridge SC is substantially parallel with the bottom face of
the seed cartridge accommodating part da or the surface of the
flange part f.
In this state, the cover sheet ST is arranged to cover
the opening of the recess part d to make the cover sheet ST and
the flange part f adhere airtightly, and thus the cartridge C
can be hermetically sealed in the plastic case PK.
[0051]
CA 02886802 2015-03-30
. .
In addition, by bonding the cover sheet ST on the flange
part f of the accommodation case PC, the cartridge C is
restricted from moving in its axial direction. This is because
when the cartridge C is about to move in the axial direction,
the axial end face of the magazine M comes into contact with
the wall face that connects the magazine accommodating part db
and the seed cartridge accommodating part da and so on, and can
no longer move.
When the cover sheet ST is bonded on the flange part f
of the accommodation case PC, the cartridge C is restricted from
rotating about its axis. This is because the surface of the
seed cartridge SC is in surface contact with the bottom face
of the seed cartridge accommodating part da, or there is only
a small gap between these.
[0052]
Therefore, the cartridge C being accommodated in the
plastic case PK is held in the state that the axial direction
of the cartridge C substantially coincides with the axial
direction of the recess part d (namely, axial direction of the
container PK) , and the surface of the seed cartridge SC is almost
parallel with the surface of the flange part f (top face in Fig.
10).
[0053]
(Description of radiation intensity measuring apparatus 1 of
the present embodiment)
36
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CA 02886802 2015-03-30
Next, the radiation intensity measuring apparatus 1 of
the present embodiment will be described. Before describing
the details of each part of the apparatus, the structure of the
apparatus and the operation thereof will be briefly described.
[0054]
In Fig. 1 to Fig. 4, the reference numeral 2 denotes a
base of the radiation intensity measuring apparatus 1.
On the top face of the base 2, a holding means 10 is
provided. The holding means 10 has a holding plate 12 distanced
from the top face of the base 2. The holding plate 12 can
accommodate multiple cartridges C in which radiation sources
S for measuring the radiation intensity are packed, or multiple
containers PK accommodating cartridges C. The holding plate
12 is formed with a radiation emitting part 12s to make the
radiation emitted from the radiation sources S of the
accommodated cartridges C to be emitted in the space between
the top face of the base 2 and the holding plate 12 (see Fig.
3, hereinafter, referred to as a measurement space 1h) (see Fig.
8).
[0055]
On the other hand, in the measurement space lh, a moving
means 20 and a radiation intensity measuring means 30 are
disposed.
The radiation intensity measuring means 30 measures the
intensity of the radiation emitted from the radiation source
37
CA 02886802 2015-03-30
. .
=
S of the cartridge C.
The moving means 20 moves the radiation intensity
measuring means 30 in the measurement space lh. Concretely,
the moving means 20 has a function of moving the radiation
intensity measuring means 30 toward or away from the multiple
cartridges C accommodated in the holding plate 12.
[0056]
Since the configuration as described above is employed,
by accommodating multiple cartridges C each packed with the
radiation sources S for which the radiation intensity is to be
measured, in the holding plate 12, and sequentially moving the
radiation intensity measuring means 30 toward the multiple
cartridges C accommodated in the holding plate 12 by the moving
means 20, it is possible to sequentially measure the radiation
intensity of the radiation sources S packed in the multiple
cartridges C. That is, it is possible to successively measure
the radiation intensity of the radiation sources S packed in
the multiple cartridges C.
[0057]
As a result, it is no longer necessary to replace the
measured cartridge C with the cartridge C to be measured next
every time the radiation intensity of the radiation sources S
packed in each cartridge C is measured. Therefore, it is
possible to reduce the operation time required for measuring
the radiation intensity of the radiation sources S packed in
38
CA 02886802 2015-03-30
. .
=
the multiple cartridges C.
[0058]
Of course, the holding plate 12 may be structured to
accommodate only one cartridge C or container PR accommodating
the cartridge C. As descried above, by employing the structure
capable of accommodating multiple cartridges C and so on, it
is possible to obtain the merit of avoiding the necessity of
replacing the measured cartridge C with the cartridge C to be
measured next every time. On the other hand, by employing the
structure capable of accommodating only one cartridge C in the
holding plate 12, it is possible to obtain the merit of
downsizing the holding plate 12, and thus downsizing the
apparatus itself.
[0059]
In the following, each part of the radiation intensity
measuring apparatus 1 according to the present embodiment will
be described in detail.
[0060]
(Base 2)
In Fig. 1 to Fig. 4, the reference numeral 2 denotes a
base of the radiation intensity measuring apparatus 1. The base
2 is formed, for example, of a plate-like member, however, the
method for forming the base 2 is not particularly limited.
[0061]
(Frame part 11)
39
CA 02886802 2015-03-30
. .
. .
As shown in Fig. 1 to Fig. 4, on the top face of the base
2, the holding means 10 is provided. The holding means 10 has
a frame part 11 and the holding plate 12.
The frame part 11 is provided for holding the holding
plate 12 in the state that it is displaced from the top face
of the base 2. Concretely, the frame part 11 has multiple leg
parts ha standing on the top face of the base 2, and a holding
part llb disposed on the tip ends of the multiple leg parts ha.
The holding part llb is formed with an accommodation hole 11h
into which the holding plate 12 is to be set (see Fig. 2) . The
accommodation hole 11h is formed with a supporting edge llf on
a flange, at the open end edge on the side of the base 2.
Since the frame part 11 has such a structure, by setting
the holding plate 12 in the accommodation hole 11h of the holding
part 11b, it is possible to keep the holding plate 12 at a
position distanced from the top face of the base 2 by
approximately the length of the multiple leg parts lla.
[0062]
The frame part 11 is only required to be able to hold the
holding plate 12 in the state that it is distanced from the top
face of the base 2 for allowing formation of the measurement
space lh, and its structure is not limited to the aforementioned
structure. For example, the holding part llb may be supported
by a single leg part 11a, or the holding part llb may be supported
by multiple walls in place of the leg parts ha. The ability
CA 02886802 2015-03-30
, .
' .
to hold the holding plate 12 is desired to prevent occurrence
of motion, vibration or the like that will cause a measurement
error, particularly during operation of the moving mechanism
20. When the holding part llb is supported by the multiple walls,
leakage of the radiation can be prevented because the interior
of the measurement space lh can be hermetically sealed to some
extent, however, the sensor can drift due to the temperature
elevation in the measurement space lh. Therefore, when the
holding part lib is supported by multiple walls, it is desired
to provide a fan or the like for cooling the measurement space
lh.
[0063]
The method for holding the holding plate 12 positioned
in the accommodation hole 11h is not particularly limited. By
providing the supporting edge llf as described above, it is
possible to position the holding plate 12 in the accommodation
hole 11h by placing the holding plate 12 on the supporting edge
llf.
Further, a groove or the like may be formed in the
circumferential edge part of the holding plate 12, and a
projection that can be accommodated in the groove may be
provided in the inner face of the accommodation hole llh. This
structure further gives the merit of achieving positioning
while supporting the holding plate 12 by the projection.
[0064]
41
CA 02886802 2015-03-30
. .
. .
(Holding plate 12)
As illustrated in Fig. 8, the holding plate 12 is a member
formed, for example, of stainless as a raw material, and is
formed of a plate-like member. The holding plate 12 has a
substantially similar shape to the accommodation hole 11h of
the holding part lib of the frame part 11 as described above,
and is formed to be slightly smaller than the accommodation hole
11h. Concretely, it is formed into such a size that the holding
plate 12 will little rattle in the accommodation hole 11h in
the state that the holding plate 12 is positioned in the
accommodation hole 11h. For example, it is so formed that when
the holding plate 12 is positioned in the accommodation hole
11h, a gap Da formed between the holding plate 12 and the inner
face of the accommodation hole 11h is about 0.06 to 0.12 mm (see
Fig. 1) . By forming the holding plate 12 to have such a shape
and size, it is possible to prevent occurrence of motion,
vibration or the like that will cause a measurement error in
the holding plate 12 during operation of the moving mechanism
20 which is described later. Also, even if the position where
the holding plate 12 is positioned in the accommodation hole
11h deviates slightly, occurrence of a measurement error caused
by the positional deviation can be prevented.
[0065]
When the aforementioned structure in which the holding
plate 12 is supported by the supporting edge llf is employed,
42
CA 02886802 2015-03-30
a step may be provided in a later-described opposed face 12a
of the holding plate 12 as illustrated in Fig. 8(B). That is,
the structure that the step is caught by the supporting edge
llf when the holding plate 12 is positioned in the accommodation
hole llh may be employed (see the part enclosed by the circle
in Fig. 8(B)). In this case, the holding plate 12 can be made
into a more stable state in the accommodation hole llh, and the
opposed face 12a of the holding plate 12 can be made
substantially flush with the surface of the holding part 11b,
so that it becomes easier to move the radiation intensity
measuring means 30 toward the opposed face 12a of the holding
plate 12.
[0066]
Also, as illustrated in Fig. 8, the holding plate 12 is
formed with multiple accommodation grooves 12g. The multiple
accommodation grooves 12g are provided in multiple columns and
multiple rows. The multiple accommodation grooves 12g are
formed to be substantially parallel with each other.
Concretely, they are provided so that the axial directions AL
of the accommodation grooves 12g are parallel with each other.
The axial directions AL of the accommodation grooves 12g are
parallel with the y direction in Fig. 1 when the holding plate
12 is positioned in the accommodation hole llh (see Fig. 1).
[0067]
The accommodation groove 12g is formed to be recessed from
43
CA 02886802 2015-03-30
. .
. .
one face of the holding plate 12 (left face in Fig. 8(B),
hereinafter referred to as a supply face 12b) toward the other
face (right face in Fig. 8, hereinafter referred to as an opposed
face 12a). The accommodation groove 12g is so provided that
the axial direction of the cartridge C is substantially parallel
with the axial direction AL of the accommodation groove 12g when
the container PK is put into the accommodation groove 12g in
such a manner that the top face of the container PK (top face
in Fig. 10) faces with an inner bottom face b of the accommodation
groove 12g. In other words, it is so provided that the
arrangement direction of the radiation sources S packed in the
cartridge C is substantially parallel with the axial direction
AL of the accommodation groove 12g, and the axial direction of
the radiation source S is substantially parallel with the
opposed face 12a.
[0068]
For example, the supply face 12b and the opposed face 12a
of the holding plate 12 are formed parallel with each other.
And the depth of the accommodation groove 12g is preliminarily
adjusted so that the top face of the flange part f is almost
in surface contact with the supply face 12b when the container
PK is put into the accommodation groove 12g. As a result, it
is possible to bring the posture of the radiation source S into
the state as described above by putting the container PK into
the accommodation groove 12g.
44
CA 02886802 2015-03-30
. w
. .
[0069]
In addition, the accommodation groove 12g is formed into
such a shape that the container PK put into the accommodation
groove 12g as described above will not move.
For example, when the inner lateral face of the
accommodation groove 12g is formed to have substantially the
same shape as the outer lateral face of the accommodation case
PC of the container PK, the container PK can be accommodated
in such a manner that it will not move in the accommodation groove
12g while the posture of the radiation source S is brought into
the state as described above.
[0070]
The shape of the accommodation groove 12g is not
particularly limited as far as it can accommodate the container
PK immovably in the accommodation groove 12g. For example, the
container PK can be held in the accommodation groove 12g
immovably also by providing a part capable of sandwiching and
holding the recess part d of the accommodation case PC of the
container PK.
[0071]
In this accommodation groove 12g, at the position
corresponding the position where the seed cartridge SC is
located when the container PK is positioned in the accommodation
groove 12g (the seed cartridge SC corresponding position), a
radiation emitting part 12s is provided. Concretely, the
CA 02886802 2015-03-30
o *
-
radiation emitting part 12s is formed so that the radiation
emitting part 12s and the seed cartridge SC almost overlap with
each other in a plan view when the container PK is positioned
in the accommodation groove 12g.
[0072]
The radiation emitting part 12s is provided for emitting
the radiation emitted from the radiation source S, to the
measurement space lh from the opposed face 12a (see Fig. 7).
Concretely, the accommodation groove 12g is formed so that its
inner bottom face has such a thickness (distance from the inner
bottom face b to the opposed face 12a) that the radiation emitted
from the radiation source S cannot transmit therethrough. On
the other hand, at the position corresponding to the seed
cartridge SC of the accommodation groove 12g, a through hole
that penetrates the inner bottom face b of the accommodation
groove 12g and the opposed face 12a is formed as the radiation
emitting part 12s.
[0073]
As a result, when the container PK is positioned inside
the accommodation groove 12g, the radiation emitted from the
radiation source S passes through only the radiation emitting
part 12s and is irradiated inside the measurement space lh (see
Fig. 7). In addition, since the radiation emitting part 12s
is provided to almost overlap with the seed cartridge SC in a
plan view, the radiation emitted from the radiation source S
46
CA 02886802 2015-03-30
directly passes through the radiation emitting part 12s.
Accordingly, attenuation of radiation in passing through the
radiation emitting part 12s can be suppressed, and thus
measurement of the radiation intensity by the later-described
radiation intensity measuring means 30 can be accurately
executed.
[0074]
For example, in the stainless-steel holding plate 12, the
thickness of the inner bottom face b of the inner accommodation
groove 12g is about 1.9 to 2.1 mm, and the distance from the
opposed face 12a to the seed cartridge SC in the state that the
container PK is positioned in the accommodation groove 12g is
about 7.4 to 7.6 mm. And the length Li in the axial direction
of the radiation emitting part 12s (in other words, the axial
direction of the accommodation groove 12g) is about 8.5 to 8.7
mm, and the length W1 in the width direction is about 15.9 to
16.1mm. Then, the radiation emitted from the radiation source
S is partly shielded by the holding plate 12, however, most of
the radiation can be irradiated in the measurement space lh.
Also, it is possible to reduce the proportion of the radiation
emitted from the radiation emitting part 12s in the radiation
reflected in the accommodation groove 12g.
[0075]
The radiation emitting part 12s is not necessarily a
through hole as described above. The radiation intensity
47
CA 02886802 2015-03-30
. .
measuring part may have any structure as far as it can transmit
the radiation emitted from the radiation source S, and can grasp
the radiation intensity emitted from the radiation source S by
measuring the intensity of the transmitted radiation by means
of the radiation intensity measuring means 30. For example,
only the part of the radiation emitting part may be made of a
material easily transmitting radiation, or only the part of the
radiation emitting part may have a very small thickness compared
with the remaining part of the accommodation groove 12g.
However, by embodying the radiation emitting part by the through
hole as described above, the structure of the holding plate 20
can be simplified, and the merit of reducing attenuation of
radiation between the multiple radiation sources S and the
sensor is obtained.
[0076]
Also, the holding plate 12 may have a cover plate which
is attached to the supply face 12b thereof. By using a cover
plate having a structure capable of suppressing motion of the
container PK in the accommodation groove 12g when attached to
the supply face 12b, it is possible to securely prevent the
container PK from moving in the accommodation groove 12g during
measurement.
For example, the accommodation groove 12g is formed so
that the flange part f of the container PK is positioned in
surface contact with the supply face 12b. In this case, as
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CA 02886802 2015-03-30
illustrated in Fig. 7, by attaching the plate-like cover plate
PT to the supply face 12b of the holding plate 12, it is possible
to sandwich and hold the flange part f between the cover plate
PT and the supply face 12b (see Fig. 7) . And thus, it is possible
to securely prevent the container PK from moving inside the
accommodation groove 12g.
In particular, when the cover plate is made of a material
that does not transmit radiation or the cover plate has such
a thickness that does not transmit radiation, it is possible
to prevent the radiation from being emitted outside from the
side of the supply face 12b. In this case, when the radiation
intensity measuring apparatus 1 according to the present
embodiment is positioned inside a case or the like, it is easier
to prevent the radiation leakage to the outside.
[0077]
(Moving means 20)
As illustrated in Fig. 3, in the measurement space lh
between the base 2 and the holding plate 12, the moving mechanism
20 is provided. The moving mechanism 20 includes a moving frame
21, an x-direction moving mechanism 22 for moving the radiation
intensity measuring means 30 in the x direction, a y-direction
moving mechanism 23 for moving the radiation intensity
measuring means 30 in the y direction, and a controller 25 for
controlling operations of the x-direction moving mechanism 22
and the y-direction moving mechanism 23.
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CA 02886802 2015-03-30
[0078]
The y direction used herein is the y direction shown in
Fig. 1, and is parallel with the axial direction of the
accommodation groove 12h of the holding plate 12 when the
holding plate 12 is positioned in the accommodation hole 11h
of the holding part llb of the frame part 11. In other words,
the y direction means the direction parallel with the
arrangement direction of the radiation sources S that are
hermetically sealed in the container PK and accommodated in the
cartridge C accommodated in the accommodation groove 12h of the
holding plate 12. The x direction means the direction that is
parallel with the opposed face 12a of the holding plate 12 when
the holding plate 12 is positioned in the accommodation hole
11h of the holding part lib of the frame part 11, and is
orthogonal to the y direction.
[0079]
(X-direction moving mechanism 22)
As illustrated in Fig. 3, on the top face of the base 2,
a rack 22a and a rail 22b of the x-direction moving mechanism
22 are provided along the x direction. The rail 22b is provided
with a slider 22s that is movable along the axial direction of
the rail 22b. The slider 22s is fixed to the moving frame 21
as described above. To the moving frame 21, an x-direction
driving motor 22m such as a stepping motor is attached. The
x-direction driving motor 22m is provided so that its main shaft
CA 02886802 2015-03-30
=
is parallel with the y direction. To the main shaft of the
x-direction driving motor 22m, a pinion 22p is attached, and
the pinion 22p meshes with the rack 22a.
Therefore, by operating the x-direction driving motor 22m,
it is possible to move the moving frame 21 along the axial
direction of the rack 22a (x direction) together with the
x-direction driving motor 22m in association with the rotation
of the pinion 22p. In addition, since the moving frame 21 is
supported by the rail 22b via the slider 22s, the moving frame
21 can be moved stably and smoothly along the x direction.
[0080]
(Y-direction moving mechanism 23)
As illustrated in Fig. 3 and Fig. 4, to the moving frame
21, a y-direction driving motor 23m such as a stepping motor
is attached. The y-direction driving motor 23m is provided so
that its main shaft is parallel with the y direction. To the
main shaft of the y-direction driving motor 23m, a screw shaft
23a is connected. The screw shaft 23a is attached to the moving
frame 21 so that it is in parallel with the y direction. To
the screw shaft 23a, a male screw formed in the later-described
radiation intensity measuring means 30 is screwed together.
Therefore, by operating the y-direction driving motor 23m
to rotate the screw shaft 23a, it is possible to move the
radiation intensity measuring means 30 along the axial
direction of the screw shaft 23a (y direction) in association
51
CA 02886802 2015-03-30
with the rotation of the screw shaft 23a.
[0081]
(Controller 25)
As illustrated in Fig. 3, the x-direction driving motor
22m of the x-direction moving mechanism. 22 and the y-direction
driving motor 23m of the y-direction moving mechanism 23 are
electrically connected with the controller 25. The controller
25 controls the operation amounts (namely, rotation amount,
rotation direction, operation timing) of the x-direction
driving motor 22m and the y-direction driving motor 23m.
The controller 25 stores the information about the
position where the radiation emitting part 12s of each
accommodation groove 12g is located when the holding plate 12
is positioned in the accommodation hole 11h of the holding part
lib of the frame part 11, and about the axial direction of each
accommodation groove 12g. Based on the information, the
controller 25 controls the operations of the x-direction
driving motor 22m and the y-direction driving motor 23m so that
the radiation intensity of the radiation source S of the
cartridge C accommodated in each accommodation groove 12g is
sequentially measured by the radiation intensity measuring
means 30.
[0082]
By operating the x-direction driving motor 22m and the
y-direction driving motor 23m of the moving mechanism 20 by the
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. .
=
controller 25 in the manner as described above, it is possible
to move the radiation intensity measuring means 30 in the y
direction while moving the moving frame 21 in the x direction.
That is, by appropriately operating the x-direction driving
motor 22m and the y-direction driving motor 23m by the
controller 25, it is possible to position the radiation
intensity measuring means 30 at a predetermined position on the
xy plane (that is, the plane parallel with the opposed face 12a
of the holding plate 12) in the measurement space lh, and it
is possible to move the radiation intensity measuring means 30
in a desired direction along the xy plane. By operating only
one of the x-direction moving mechanism 22 and the y-direction
moving mechanism 23 while stopping operation of the other of
the same, it is possible to move the radiation intensity
measuring means 30 along the x direction or the y direction.
[0083]
Therefore, by moving the radiation intensity measuring
means 30 by the moving mechanism 20, it is possible to
sequentially measure the radiation intensity of the radiation
sources S in the cartridge C accommodated in each accommodation
groove 12g by the radiation intensity measuring means 30.
[0084]
The moving frame 21 may be provided with a guide axis 23b
provided parallel with the screw shaft 23a, and the radiation
intensity measuring means 30 may be attached to the guide axis
53
CA 02886802 2015-03-30
' .
23b so as to be movable along the axial direction of the guide
axis 23b. As a result, it is possible to move the radiation
intensity measuring means 30 along the y direction while it is
supported at least at two points, and thus it is possible to
move the radiation intensity measuring means 30 in a stable
posture.
[0085]
The configuration of the moving mechanism 20 is not
limited to the aforementioned configuration, and any mechanism
capable of moving the radiation intensity measuring means 30
parallel with the plane that is parallel with the opposed face
12a of the holding plate 12 can be employed. For example, a
screw-nut mechanism can be employed as the x-direction moving
mechanism, and a rack-pinion mechanism can be employed as the
y-direction moving mechanism. Further, the moving frame 21 can
be moved by a cylinder mechanism.
[0086]
(Radiation intensity measuring means 30)
As illustrated in Fig. 3 and Fig. 4, the radiation
intensity measuring means 30 has a sensor 31 for measuring
radiation intensity, a sensor holding part 32 for holding the
sensor 31, and a shielding member 35 provided for restricting
the radiation irradiated to the sensor 31.
[0087]
First, the sensor 31 has a detecting part 31a for
54
CA 02886802 2015-03-30
' .
measuring radiation intensity on its one face. The sensor 31
has a function of converting the intensity of the radiation
irradiated to the detecting part 31a into an electric signal
and outputting the electric signal.
[0088]
The sensor holding part 32 is a member for holding the
sensor 31. The sensor holding part 32 has a supporting part
32a for supporting the sensor 31, and a connecting part 32b for
connecting the supporting part 32a to the moving mechanism 20.
[0089]
First, to the supporting part 32a, the sensor 31 is
attached. Concretely, the sensor 31 is attached to the
supporting part 32a in such a manner that the detecting part
31a of the sensor 31 faces with the opposed face 12a of the
holding plate 12. In addition, the supporting part 32a has a
lateral wall provided to cover the lateral face of the sensor
31, and thus prevents the radiation from being irradiated to
'
the detecting part 32a of the sensor 31 from the lateral side.
[0090]
The supporting part 32a is connected to the moving
mechanism 20 by the connecting part 32b. Concretely, the
connecting part 32b is formed with a female screw hole, and a
guide hole provided parallel with the female screw hole. And
the screw shaft 23a is screwed into the female screw hole, and
the guide axis 23b is penetrated in the guide hole.
CA 02886802 2015-03-30
, 1
=
[0091]
Therefore, as the screw shaft 23a rotates, the connecting
part 32b moves along the screw shaft 23a, so that it is possible
to move the sensor 31 fixed to the supporting part 32a that is
connected to the connecting part 32b along the axial direction
(y direction) of the screw shaft 23a.
[0092]
As illustrated in Fig. 3 and Fig. 4, the shielding member
35 is provided to cover the detecting part 31a of the sensor
31 held by the sensor holding part 32. In other words, the
shielding member 35 is provided so that it is positioned between
the detecting part 31a of the sensor 31 held by the sensor holding
part 32, and the opposed face 12a of the holding plate 12. The
shielding member 35 restricts the radiation irradiated to the
detecting part 31a of the sensor 31 when the radiation is emitted
from the radiation emitting part 12s of the holding plate 12.
[0093]
Concretely, the shielding member 35 is a member formed
of a material that radiation fails to transmit or difficult to
transmit therethrough (for example, brass, copper, tungsten and
so on) or a stainless plate, formed into a material having a
thickness through which the radiation cannot transmit (for
example, about 7 to 9 mm) . The shielding member 35 is formed
with a slit 35h. The slit 35h is formed to pass through the
face opposed to the opposed face 12a of the holding plate 12
56
CA 02886802 2015-03-30
, .
(shielding face) and the face opposed to the detecting part 31a
of the sensor 31 in the shielding member 35. That is, by
providing the shielding member 35, only the radiation passing
through the slit 35h of the radiation emitted from the radiation
emitting part 12s of the holding plate 12 is irradiated to the
detecting part 31a of the sensor 31 when the radiation intensity
measuring means 30 is positioned below the radiation emitting
part 12s of the holding plate 12.
[0094]
The slit 35h is formed so that its axial direction is
parallel with the x direction in the state that the radiation
intensity measuring means 30 is attached to the moving means
20. That is, the slit 35h is formed in the direction orthogonal
to the arrangement direction of the radiation sources S, or in
other words, in the direction parallel with the axial directions
of the radiation sources S. In addition, the slit 35h is formed
so that its width W2 is smaller than the wire diameter of the
radiation source S.
[0095]
With the above configuration, the radiation intensity
measuring means 30 is moved below the radiation emitting part
12s of the accommodation groove 12g in which the cartridge C
to be measured is accommodated, and the radiation intensity
measuring means 30 is moved along the axial direction of the
accommodation groove 12g (that is, the arrangement direction
57
CA 02886802 2015-03-30
. .
=
of the radiation sources S) by means of the moving mechanism
20. As a result, it is possible to measure the intensity of
the radiation emitted from the multiple radiation sources S
packed in the cartridge C to be measured.
[0096]
In addition, the width W2 (see Fig. 4) of the slit 35h
is smaller than the wire diameter of the radiation source S,
and the axial direction of the slit 35h is parallel with the
axial direction of the radiation source S. Therefore, when the
radiation intensity measuring means 30 is moved along the axial
direction of the accommodation groove 12g (that is, the
arrangement direction of the radiation sources S), the
radioactivity of each radiation source S can be calculated based
on the variation in radiation intensity of the radiation source
S detected by the detecting part 31a of the sensor 31. For
example, the slit 35h may have the width W2 ranging from 0.05
to 0.15 mm, and the axial length ranging from 9 to 11 mm.
[0097]
In measuring the radiation intensity of the radiation
source S held by the aforementioned cartridge 03, there is the
case where one accommodation groove 12g is provided with
multiple radiation emitting parts 12s. In this case, the
cartridge 03 is positioned so that each one of the radiation
sources S is allocated to each radiation emitting part 12s.
Then, by means of the moving mechanism 20, the radiation
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CA 02886802 2015-03-30
intensity measuring means 30 is sequentially moved below each
radiation emitting part 12s in the accommodation groove 12g
where the cartridge C to be measured is accommodated, and the
radiation intensity measuring means 30 is moved along the
direction intersecting with the axial direction of each
radiation source S (preferably, the direction orthogonal to the
axial direction of the radiation source S) . Thus, the intensity
of the radiation emitted from each radiation source S packed
in the cartridge C3 to be measured can be individually measured.
[0098]
In measuring the radiation intensity of the radiation
source S held by the aforementioned shaft-shaped cartridge 03,
as described above, the slit-like radiation emitting part 12s
may be provided in place of providing multiple radiation
emitting parts 12s in one accommodation groove 12g. Also in
this case, the radiation intensity measuring means 30 is
sequentially moved below each radiation source S in the
cartridge 03 to be measured by means of the moving mechanism
20. For each radiation source S, by moving the radiation
intensity measuring means 30 along the direction intersecting
with the axial direction thereof (preferably, the direction
orthogonal to the axial direction of the radiation source S),
it is possible to individually measure the intensity of the
radiation emitted from each radiation source S packed in the
cartridge C to be measured.
59
CA 02886802 2015-03-30
, $
,
=
[ 0 0 9 9 1
Further, the shielding member 35 of the radiation
intensity measuring means 30 is preferably provided so that the
shielding face thereof on the side of the holding plate 12 is
parallel with the opposed face 12a of the holding plate 12.
Since the radiation intensity measuring means 30 moves parallel
with the opposed face 12a by means of the moving mechanism 20,
interference between the holding plate 12 and the shielding
member 35 can be prevented even when the gap between the holding
plate 12 and the shielding member 35 is narrowed in the
aforementioned configuration of the shielding member 35. In
other words, it is possible to reduce the distance between the
opposed face 12a of the holding plate 12 and the shielding member
35. As a result, it is possible to prevent the radiation having
passed through the neighboring radiation emitting part 12s from
being irradiated to the sensor face 31a of the sensor 31 through
the slit 35h during measurement of the radiation passing through
one radiation emitting part 12s. For example, the radiation
emitting part 12s has the size as described in the paragraph
0074, and the slit 35h has the size as described in the paragraph
0096. In this case, as shown in Fig. 7, radiation is emitted
from each radiation emitting part 12s. By setting the gap Db
between the holding plate 12 and the shielding member 35 at 0.5
to 1.5 mm, it is possible to prevent the radiation having passed
through the neighboring radiation emitting part 12s from being
CA 02886802 2015-03-30
irradiated to the sensor face 31a of the sensor 31 through the
slit 35h even if the distance DX in the x direction between the
neighboring radiation emitting parts 12s is set at 45 to 47 mm,
and the distance DY in the y direction is set at 84 to 86 mm
(see Fig. 8).
[0100]
The opposed face 12a of the holding plate 12 as described
above corresponds to the reference face in claim 9.
[0101]
(Radiation intensity measuring operation)
Next, measurement of the radiation intensity by the
radiation intensity measuring apparatus 1 according to the
present embodiment will be specifically described.
[0102]
First, in each multiple accommodation groove 12g in the
holding plate 12, the container PK is accommodated, and the
holding plate 12 is positioned in the accommodation hole llh
of the holding part 11b. Then in each cartridge C accommodated
in the multiple accommodation grooves 12g, the arrangement
direction of the packed multiple radiation sources S
substantially coincides with the axial direction AL of each
accommodation groove 12g. Therefore, in the state that the
holding plate 12 is positioned in the accommodation hole llh
of the holding part 11b, the arrangement direction of the
multiple radiation sources S packed in each cartridge C is
61
CA 02886802 2015-03-30
. q
,
parallel with the y direction, and the axial directions of the
multiple radiation sources S are parallel with the x direction.
[0103]
On the other hand, the slit 35h of the shielding member
35 of the radiation intensity measuring means 30 is formed so
that its axial direction is parallel with the x direction.
Therefore, the radiation intensity measuring means 30 is moved
by the x-direction moving mechanism 22 to the position where
the plane dividing the slit 35h into two halves in its axial
direction contains the axial direction AL of one accommodation
groove 12g. And thus, preparation for measuring the radiation
intensity of the multiple radiation sources S packed in the
cartridge C accommodated in one accommodation groove 12g
completes.
Hereinafter, the state that the radiation intensity
measuring means 30 is positioned as described above for each
accommodation groove 12g is referred to as a measurement standby
state.
[0104]
Then as the radiation intensity measuring means 30 is
positioned in the measurement standby state, the radiation
intensity measuring means 30 is moved in the y direction by means
of the y-direction moving mechanism 23. Then, the slit 35h
passes below the radiation emitting part 12s of one
accommodation groove 12g while keeping its axial direction
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CA 02886802 2015-03-30
. ,
parallel with the axial direction of the multiple radiation
sources S. And thus, the intensity of the radiation emitted
from each of the multiple radiation sources S packed in the
cartridge C accommodated in one accommodation groove 12g is
measured by the detecting part 31a of the sensor 31. At this
time, since the width of the slit 35h is formed to be smaller
than the wire diameter of the radiation source S, the radiation
intensity detected by the detecting part 31a of the sensor 31
varies with the movement of the slit 35h.
[0105]
Concretely, since the width of the slit 35h is smaller
than the wire diameter of the radiation source S, only part of
the radiation emitted from the radiation source S passes through
the slit 35h, and only the radiation having passed through the
slit 35h is detected by the detecting part 31a of the sensor
31. Since the radiation emitted from the radiation source S
is emitted radially from the center axis of the radiation source
S (see Fig. 7), the radiation intensity detected by the
detecting part 31a of the sensor 31 peaks when the center axis
of the slit 35h and the center axis of the radiation source S
coincide with each other, and decreases as the deviation
therebetween increases. Therefore, the radiation intensity
detected by the detecting part 31a of the sensor 31 varies with
the movement of the slit 35h as far as the axial direction of
the slit 35h is kept parallel with the axial direction of the
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CA 02886802 2015-03-30
' .
radiation source S during its movement. That is, the radiation
intensity varies in such manner that it peaks when the center
axis of the slit 35h coincides with the center axis of each
radiation source S, and reaches a trough when the center axis
of the slit 35h is positioned between the center axes of the
neighboring radiation sources S.
As a result, it is possible to calculate the radioactivity
of each radiation source S based on the variation in measured
radiation intensity, concretely, the number of peaks of the
radiation intensity, the peak value, and the peak timing.
[0106]
After completion of measurement of all the radiation
sources S packed in the cartridge C accommodated in one
accommodation groove 12g, the radiation intensity measuring
means 30 is moved by the moving mechanism 20 so that the
accommodation groove 12g in which the cartridge C to be measured
next is accommodated is brought into the measurement standby
state. Then, as the radiation intensity measuring means 30 is
positioned in the measurement standby state, the radiation
intensity measuring means 30 is moved in the y direction by the
moving mechanism 20. Then, the intensity of the radiation
emitted from the multiple radiation sources S packed in the
cartridge C accommodated in the accommodation groove 12g is
measured by the detecting part 31a of the sensor 31.
[0107]
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CA 02886802 2015-03-30
. .
. .
After completion of measurement of the multiple radiation
sources S packed in the cartridge C accommodated in this
accommodation groove 12g, the radiation intensity measuring
means 30 is moved so that the accommodation groove 12g in which
the cartridge C to be measured next is accommodated is brought
into the measurement standby state, and then the radiation
intensity is measured.
[0108]
The above-described operation is repeated until
measurement of the radiation sources S packed in all the
cartridges C completes. After completion of measurement of the
radiation sources S packed in all the cartridges C, the holding
plate 12 is detached from the frame part 11, and the next holding
plate 12 is positioned. At this time, by preliminarily setting
the container PK in the next accommodation groove 12g of the
holding plate 12, it is possible to replace the cartridges C
to be measured only by positioning the next holding plate 12.
In addition, since plural cartridges C can be replaced
at once, it is possible to replace the cartridge C to be measured
in a very short time, and to suppress the radiation exposure
to the operator.
[0109]
According to the radiation intensity measuring apparatus
1 of the present embodiment having the aforementioned
configuration, by accommodating the cartridge C in which the
CA 02886802 2015-03-30
multiple radiation sources S are packed in the accommodation
groove 12g, and moving the radiation intensity measuring means
30 by the moving mechanism 20, it is possible to measure the
radiation intensity of each radiation source S at one
measurement while keeping the multiple radiation sources S
(that is, all the radiation sources S packed in the cartridge
C) packed in the cartridge C. Therefore, it is possible to
measure the radioactivity of the multiple radiation sources S
packed in the cartridge C in a short time.
[0110]
Further, since the variation in the radiation intensity
is measured by moving the slit 35h (that is, radiation intensity
measuring means 30), it is possible to grasp a peak value or
the presence or absence of a peak value in the variation curve
of the radiation intensity even when there is some variation
in the packing interval of the radiation sources S.
Therefore, even if the position of the radiation source
S held in the cartridge C is somewhat misaligned, it is possible
to measure the radiation intensity of each radiation source S
accurately.
[0111]
The speed at which the radiation intensity measuring
means 30 moves in the arrangement direction of the radiation
sources S is not particularly limited, and may be any speed at
which variation in the radiation intensity required for
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CA 02886802 2015-03-30
. t
calculation of the radioactivity of each radiation source S can
be measured.
[0112]
Further, since the multiple cartridges C are held in the
holding plate 12, it is possible to sequentially move the
radiation intensity measuring means 30 so that the holding
groove 12g accommodating each cartridge C is brought into the
measurement standby state, and it is possible to sequentially
measure the radiation intensity of the multiple radiation
sources S in each cartridge C. By moving the radiation
intensity measuring means 30 by the moving mechanism 20, it is
possible to successively measure the radiation intensity of the
multiple radiation sources S in the multiple cartridges C.
[0113]
When only part of the radiation sources S among the
multiple radiation sources S packed in the cartridge C are
intended to be measured, it is not necessary to make the slit
35h pass through the position of every radiation source S. but
it is only required to move the radiation intensity measuring
means 30 so that the slit 35h passes through the position of
the radiation source S that is intended to be measured.
Similarly, in the case of measuring only the multiple
radiation sources S packed in part of cartridges C held in the
holding plate 12, only the target cartridge C may be measured.
[0114]
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CA 02886802 2015-03-30
1
The aforementioned state from positioning the radiation
intensity measuring means 30 in one accommodation groove 12g
to establish the measurement standby state, to completion of
measurement of the radiation intensity for the radiation
sources S packed in the cartridge C accommodated in the one
accommodation groove 12g corresponds to a measurement state
described in claims.
[0115]
In the aforementioned embodiment, the shielding face of
the shielding member 35 is kept parallel with the opposed face
12a of the holding plate 12 and also the axial direction of the
slit 35h is kept parallel with the x direction in the state other
than the measurement state. However, the posture of the
shielding face of the shielding member 35 and the positioning
in the axial direction of the slit 35h in the state other than
the measurement state are not particularly limited.
[0116]
(Regarding measurement accuracy)
In the measurement standby state, the radiation intensity
measuring means 30 is moved by the x-direction moving mechanism
22 to the position where the plane dividing the slit 35h into
two halves in its axial direction contains the axial direction
AL of one accommodation groove 12g, and then the radiation
intensity measuring means 30 is moved in the y direction. By
moving the radiation intensity measuring means 30 in this manner,
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CA 02886802 2015-03-30
. r
it is possible to accurately measure the intensity of the
radiation emitted from the radiation source S. However, in the
measurement standby state, even when the plane dividing the slit
35h into two halves in its axial direction is slightly (for
example, about 1 mm) deviated from the axial direction AL of
one accommodation groove 12g, the measurement accuracy of the
intensity of the radiation emitted from the radiation source
S does not significantly deteriorate as far as the axial length
of the slit 35h is 9 to 11 mm. Also, even when the moving
direction is slightly (for example, about 5 degrees) tilted from
the y direction in moving the radiation intensity measuring
means 30 from the measurement standby state, the measurement
accuracy of the intensity of the radiation emitted from the
radiation source S does not significantly deteriorate.
[0117]
On the other hand, when deviation in positioning the
holding plate 12 in the accommodation hole 11h of the holding
part 11b, deviation in putting the container PK into the
accommodation groove 12g, or deviation of the cartridge C in
the container PK is large, there is a possibility that the
radiation intensity cannot be measured accurately by moving the
radiation intensity measuring means 30 as described above.
However, in the radiation intensity measuring apparatus 1 of
the present embodiment, since the radiation intensity is
measured by moving the radiation intensity measuring means 30,
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CA 02886802 2015-03-30
t is possible to measure the radiation intensity accurately
without necessity of setting the holding plate 12 and the
container PK again by provision of a function of compensating
the positional deviation based on the measurement result of the
radiation intensity. Thus it is possible to reduce the time
required for setting the holding plate 12 and the container PK
again, and to suppress the radiation exposure to the operator.
[0118]
For example, when the measured radiation intensity is
generally low for all the radiation sources S in the cartridge
C, a positional deviation in the x direction can occur. In such
a case, by slightly shifting the position of the radiation
intensity measuring means 30 in the measurement standby state
in the x direction from the normal position in the measurement
standby state, it is possible to accurately measure the
radiation intensity. That is, it is possible to accurately
measure the radiation intensity without conducting the
operation of setting the holding plate 12 and the container PK
again.
[0119]
(Improvement in measurement accuracy by x-directional
movement)
When the x-directional positions of the radiation sources
S are misaligned from each other in the seed cartridge SC, after
movement of a certain degree in the y direction, the movement
CA 02886802 2015-03-30
= .
=
in the y direction is temporarily stopped, and then reciprocal
movement in the x direction may be effected. In this manner,
it is possible to accurately measure the radiation intensity
of each radiation source S even if the positions in the x
direction of the radiation sources S are misaligned each other.
[0120]
As described above, in the measurement standby state, the
radiation intensity measuring means 30 is moved by the
x-direction moving mechanism 22 to the position where the plane
dividing the slit 35h into two halves in its axial direction
contains the axial direction AL of one accommodation groove 12g,
and then the radiation intensity measuring means 30 is moved
in the y direction. Therefore, when such a state is established
that all of the line dividing the radiation source S into two
halves in its axial direction, the axial direction AL of the
accommodation groove 12g, and the plane dividing the slit 35h
into two halves in its axial direction coincide with each other
(ideal position), the radiation irradiated from the radiation
source S can be measured most efficiently by the radiation
intensity measuring means 30. However, actually it is often
the case that the position of the radiation source S is slightly
deviated in the axial direction (namely, x direction) of the
radiation source S with respect to the ideal position (see Fig.
15 (A) ) . In this case, the amount of the radiation cut by the
radiation emitting part 12s and the slit 35h increases compared
71
CA 02886802 2015-03-30
with the case where the radiation sources S are arranged in the
ideal position, and the detected radiation intensity can be
slightly smaller.
[0121]
In such a case, as described above, the radiation
intensity measuring means 30 is moved in such a manner that after
movement of a certain amount in the y direction, the movement
in the y direction is temporarily stopped, and then the
radiation intensity measuring means 30 is reciprocally moved
in the x direction (see Fig. 15(B)). Then, even at the same
y-direction position, the intensity of the radiation detected
by the detecting part 31a of the sensor 31 changes, and the
intensity peaks at a certain position. Then by calculating the
radiation intensity of the radiation source S based on the
intensity of the radiation at the position where the intensity
peaks, the calculated radiation intensity is less different
from the value of the radiation intensity in the case of
measurement in the ideal position. That is, it is possible to
accurately measure the intensity of the radiation of the
radiation source S.
[0122]
For example, when the positions in the x axial direction
of the radiation sources a to c are misaligned as illustrated
in Fig. 15(A), the intensities of the radiation sources a to
c obtained by reciprocally moving the radiation intensity
72
CA 02886802 2015-03-30
measuring means 30 in the x direction (see Fig. 15 (B) ) are as
shown in Fig. 15 (C) .
That is, in the state that the cartridge C is accommodated
in the accommodation groove 12g, when the cartridge C is
positioned so that the line dividing the axial direction into
two halves coincides with the axial direction Al of the
accommodation groove 12g as in the radiation source c, the
radiation intensity shows the variation in which the radiation
intensity peaks (for example, the curve of c in Fig. 15 (C) ) when
the radiation intensity measuring means 30 is positioned at the
position where the plane dividing the slit 35h into two halves
in its axial direction coincides with the axial direction AL
(corresponding to the position of 30c in Fig. 15 (B) , and the
position of P in Fig. 15 (C) , for example) .
On the other hand, if the line dividing the axial
direction into two halves is deviated leftward with respect to
the axial direction AL of the accommodation groove 12g as in
the radiation source a, the radiation intensity shows the
variation in which the radiation intensity peaks (for example,
the curve of a in Fig. 15 (C) ) when the radiation intensity
measuring means 30 is positioned at the position where the plane
dividing the slit 35h into two halves in its axial direction
is deviated leftward with respect to the axial direction AL (for
example, the position of 30a in Fig. 15 (B) ) .
On the contrary, if the line dividing the axial direction
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into two halves is deviated rightward with respect to the axial
direction AL of the accommodation groove 12g as in the radiation
source c, the radiation intensity shows the variation in which
the radiation intensity peaks (for example, the curve of b in
Fig. 15 (C) ) when the radiation intensity measuring means 30 is
positioned at the position where the plane dividing the slit
35h into two halves in its axial direction is deviated leftward
with respect to the axial direction AL (for example, the
position of 30b in Fig. 15 (B) ) .
In Fig. 15, rightward and leftward mean the directions
of right and left in a plan view (see Fig. 1) .
[0123]
The timing of reciprocally moving the radiation intensity
measuring means 30 in the x direction is not particularly
limited. For example, the radiation intensity measuring means
30 may be moved in such a manner that after movement of a certain
amount in the y direction, the radiation intensity measuring
means 30 is returned to the position where the peak value is
detected, and the radiation intensity measuring means 30 is
reciprocally moved in the x direction at that position. In this
case, at the current position of the radiation source S,
variation of the radiation intensity in the x direction can be
confirmed at the position where the intensity of the radiation
detected by the detecting part 31a of the sensor 31 peaks in
the y direction. That is, since the radiation intensity of the
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. I
radiation source S is measured at the position where the
radiation intensity of the radiation source S passing through
the radiation emitting part 12s and the slit 35h can be detected
maximally at the current position of the radiation source S,
it is possible to elevate the measurement accuracy of the
radiation intensity of the radiation source S.
[0124]
Further, regardless of whether a peak value is detected
at the position, the radiation intensity measuring means 30 may
be reciprocally moved in the x direction at the position reached
by movement of a certain amount in the y direction. Also in
this case, it is possible to grasp the position where the
radiation intensity can be detected maximally in the x direction.
Therefore, by correcting the radiation intensity of the
radiation source S based on the difference between the position
and the position where the plane dividing the slit 35h into two
halves in its axial direction contains the axial direction AL
of one accommodation groove 12g, it is possible to improve the
accuracy of estimating the radiation source S.
[0125]
Further, the radiation intensity measuring means 30 may
be reciprocally moved in the x direction while it is moved in
the y direction. Also in this case, by increasing the speed
of the reciprocal movement in the x direction while decreasing
the movement speed in the y direction to some extent, variation
CA 02886802 2015-03-30
in the radiation intensity in the y direction and the variation
in the radiation intensity in the x direction can be measured,
and the radiation intensity of the radiation source S can be
corrected depending on the measurement results.
[0126]
(Calibration part 40)
Regarding the radiation intensity of each radiation
source S, it is possible to grasp whether each radiation source
S is good or defective by relatively comparing respective peak
values of the radiation source S in the variation curves of
radiation intensity if their absolute values are not required.
On the other hand, in the case of grasping the absolute
value of the radiation intensity of each radiation source S,
it is desired to measure the variation curve of the radiation
intensity for the cartridge C in which a reference radiation
source having a reference radiation intensity is packed, prior
to conducting measurement of the cartridge C to be measured.
This makes it possible to grasp the absolute value of the
radiation intensity of each radiation source S packed in the
cartridge C to be measured from the measurement value (peak
value) of the cartridge C to be measured, based on the peak value
of the reference radiation source.
[0127]
Particularly, in the case of sequentially measuring the
multiple cartridges C accommodated in respective accommodation
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a
grooves 12g of the holding plate 12, the reference radiation
source may be measured as is appropriate. For example, the
reference radiation source may be measured every time before
measuring the cartridge C. Also, the reference radiation
source may be measured once before measuring the multiple
cartridges C of each holding plate 12. That is, the reference
radiation source may be measured directly after replacing the
holding plate 12, and thereafter the multiple cartridges C may
be successively measured.
[0128]
By automating the measurement of the reference radiation
source, it is possible to conduct measurement rapidly while
keeping the measurement accuracy. For example, by designing
the radiation intensity measuring means 30 to have the following
structure, and providing the calibration part 40, it is possible
to automate the measurement of the reference radiation source.
[0129]
As illustrated in Fig. 4, in the shielding member 35 of
the radiation intensity measuring means 30, the slit 35h is
formed in its distal end part. A proximal end of the shielding
member 35 is connected to the connecting part 32b of the sensor
holding part 32 in a swingable manner so that its distal end
part swings parallel with the opposed face 12a of the holding
plate 12. Concretely, the shielding member 35 is provided
movably between a measurement position where its distal end part
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= a
=
is positioned above the detecting part 31a of the sensor 31 (see
Fig. 6 (A) ) , and a calibration position where its distal end part
is moved from the detecting part 31a of the sensor 31 (see Fig.
6 (B) ) . In other words, when the distal end part of the shielding
member 35 is positioned in the measurement position, the
detecting part 31a of the sensor 31 is covered with the distal
end, and when the distal end of the shielding member 35 is
positioned in the calibration position, the detecting part 31a
of the sensor 31 is exposed.
[0130]
In addition, the connecting part 32b of the sensor holding
part 32 is provided with an urging means 36 for urging the distal
end part of the shielding member 35 toward the measurement
position from the calibration position. The urging means 36
also has a function of allowing the distal end part to swing
to the measurement position when force is applied to the
shielding member 35 in the direction of swinging the distal end
part from the measurement position to the calibration position.
And the connecting part 32b of the sensor holding part 32 is
provided with a stopper 36a that comes into contact with the
shielding member 35 when the distal end part of the shielding
member 35 is positioned in the measurement position. That is,
swinging of the shielding member 35 is restricted by the stopper
36a so that its distal end part cannot swing beyond the
measurement position. Therefore, since the distal end part of
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=
the shielding member 35 is usually pushed against the stopper
36a by the urging means 36, it is possible to keep the distal
end part of the shielding member 35 positioned in the
measurement position. For example, when a spring is used as
the urging means 36, the aforementioned function can be exerted.
[0131]
As illustrated in Fig. 5, on the back face of the holding
part lib of the frame part 11 of the holding means 10, the
calibration part 40 is provided. The calibration part 40 is
provided with a projecting part 41 projecting slightly on the
side of the base 2 from the back face of the holding part 11b.
The projecting part 41 is formed so that the distance from its
surface on the side of the base 2 to the surface of the shielding
member 35 of the radiation intensity measuring means 30 (face
on the side of the holding plate 20) is shorter than the distance
from the opposed face 12a of the holding plate 12 to the surface
of the shielding member 35.
Further, on the surface on the side of the base 2 of the
projecting part 41, a reference cartridge BC in which the
reference radiation source is packed is disposed. The
reference cartridge BC is held by the projecting part 41 so that
the axial direction of the reference radiation source is
parallel with the x direction. In other words, the reference
cartridge BC is held by the projecting part 41 so that the axial
direction of the reference radiation source is orthogonal to
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CA 02886802 2015-03-30
. .
. .
the y direction.
[0132]
Since the structure as described above is employed, as
the radiation intensity measuring means 30 is moved toward the
projecting part 41 from the y direction by the moving mechanism
20, the distal end part of the shielding member 35 comes into
contact with the projecting part 41 (Fig. 6 (A) ) . As the
radiation intensity measuring means 30 is further moved in the
y direction (the direction of the arrow in Fig. 6) from that
state, a force is applied to the distal end part of the shielding
member 35 in the direction of swinging from the measurement
position to the calibration position. As a result, the distal
end part of the shielding member 35 swings from the measurement
position toward the calibration position against the urging
force of the urging means 36. On the other hand, the sensor
31 moves below the projecting part 41.
Further, as the radiation intensity measuring means 30
is moved in the y direction, the distal end part moves from above
the detecting part 31a of the sensor 31, and the detecting part
31a of the sensor 31 is completely exposed (Fig. 6 (B) ) . Since
the exposed detecting part 31a of the sensor 31 moves to the
position facing with the reference radiation source of the
reference cartridge BC, the detecting part 31a is directly
irradiated with the radiation emitted from the reference
radiation source.
CA 02886802 2015-03-30
r
r
[0133]
Since the aforementioned configuration is employed, by
moving the radiation intensity measuring means 30 from the y
direction toward the projecting part 41 by the moving mechanism
20, it is possible to measure the intensity of the radiation
emitted from the reference radiation source by the detecting
part 31a of the sensor 31. Therefore, by conducting calibration
of the sensor with reference to the measurement result, it is
possible to keep the accuracy of estimating the radioactivity
of the radiation source S high, based on the measurement result
of the radiation intensity of the radiation source S of each
cartridge C. In particular, by conducting calibration of the
sensor 31 by the calibration part 40 every time before measuring
each cartridge C, it is possible to keep the accuracy of
estimating the radioactivity of the radiation source S of each
cartridge C high.
[0134]
In addition, only by moving the radiation intensity
measuring means 30 from the y direction toward the projecting
part 41 by the moving means 20, it is possible to conduct the
calibration of the sensor 31. That is, since calibration of
the sensor 31 can be automatically conducted, the number of
operating steps conducted by an operator remains unchanged even
when the calibration operation is conducted. Therefore, it is
possible to prevent increase in the amount of radiation exposed
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to the operator during the calibration operation.
[0135]
(Regarding holding plate 12)
In the above example, while the description was made for
the case where the cartridge C hermetically sealed in the
container PK is accommodated in the holding plate 12, the
cartridge C may be accommodated in the accommodation groove 12g
of the holding plate 12 as it is. Also in such a case, the
accommodation groove 12g may be formed so that the multiple
radiation sources S packed in the seed cartridge SC of the
cartridge C are parallel with the opposed face 12a of the holding
plate 12, and the arrangement direction of the multiple
radiation sources S coincides with the axial direction AL of
the accommodation groove 12g when the cartridge C is put into
the accommodation groove 12g.
[0136]
(Holding plate 12B for rectangular cartridge 02)
In the case of measuring the rectangular cartridge 02,
the shape of the accommodation groove 12g is made into
coincident with the shape of the rectangular cartridge 02. For
example, the holding plate 12B may have the shape as illustrated
in Fig. 14.
[0137]
As illustrated in Fig. 14, an inner bottom face b of the
accommodation groove 12g of the holding plate 12B is formed into
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CA 02886802 2015-03-30
. ,
a flat plane. As a result, when the rectangular cartridge C2
is accommodated in the accommodation groove 12g, the surface
of the main body M of the rectangular cartridge C2 can be brought
into surface contact with the inner bottom face b, with the
result that it is possible to make the center axis of the multiple
radiation sources S packed in the seed cartridge SC of the main
body M parallel with the opposed face 12a of the holding plate
12. In addition, by forming the accommodation groove 12g to
have substantially the same width as a width MD of the main body
M of the rectangular cartridge 02 (see Fig. 11 (B) ) , it is
possible to accurately measure the radiation intensity of the
multiple radiation sources S because the rectangular cartridge
C2 will not rattle in the accommodation groove 12g.
[0138]
In the rectangular cartridge C2 shown in Fig. 14, since
an attachment is provided on the lateral side of the seed
cartridge SC, it is desired to provide a groove 12d so that the
attachment will not interfere with accommodation of the
rectangular cartridge 02. The depth and width of the groove
12d are not particularly limited, and it is only required to
be able to bring the surface of the main body M of the rectangular
cartridge 02 into surface contact with the inner bottom face
b.
[0139]
By providing the grooves 12d in the manner of holding the
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accommodation groove 12g therebetween (in other words, on each
end part of the accommodation groove 12g), it is possible to
obtain the merit of making it easy to take out the rectangular
cartridge C2 from the accommodation groove 12g.
[0140]
(Holding plate 120 for shaft-shaped cartridge 03)
In the case of measuring the shaft-shaped cartridge 03
as described above, the shape of the accommodation groove 12g
in the holding plate 12C may be made into coincident with the
shape of the shaft-shaped cartridge 03.
[0141]
For example, as illustrated in Fig. 14, unlike the cases
of the holding plates 12, 125, the holding plate 120 for
shaft-shaped cartridge 03 is formed with the accommodation
groove 12g so that the axial direction is parallel with the x
direction when the holding plate 120 is attached to the holding
part llb of the frame part 11. The accommodation groove 12g
supports both ends of the shaft-shaped cartridge C3 at its both
end parts. The accommodation groove 12g is formed with a
slit-like radiation emitting part 12s penetrating the
accommodation groove 12g and the opposed face 12a between its
both end parts. In the case of the holding plate 120 described
above, it is possible to position the radiation source S
accommodated in the strap member SB above the radiation emitting
part 12s along the groove Mg of the main body M, or in other
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CA 02886802 2015-03-30
words, along the axial direction of the radiation emitting part
12s by positioning the shaft-shaped cartridge C3 in the
accommodation groove 12g. That is, since the center axis of
the shaft-shaped cartridge C3 (that is, the center axis of the
radiation source S) and the center axis of the inner bottom face
b are parallel with each other, the center axes of the multiple
radiation sources S held by the shaft-shaped cartridge C3 can
be brought into parallel with the opposed face 12a of the holding
plate 12. Then, as described above, by moving the radiation
intensity measuring means 30 along the y direction (that is,
the direction orthogonal to the axial direction of each
radiation source S) while the radiation intensity measuring
means 30 is sequentially moved below each radiation source S
in the cartridge C3 to be measured, it is possible to
individually measure the intensity of the radiation emitted
from each radiation source S.
[0142]
Also, as illustrated in Fig. 14, by providing the groove
12d in one (or both) of end parts of the accommodation groove
12g in the holding plate 12C, it is possible to obtain a merit
of making it easy to take out the shaft-shaped cartridge 03 from
the accommodation groove 12g.
[0143]
(Holding plate for connecting cartridge)
Also, in the case of measuring the aforementioned
CA 02886802 2015-03-30
i .
,
connecting cartridge, the shape of the accommodation groove 12g
may be made into coincident with the shape of the connecting
cartridge. For example, the inner bottom face b of the
accommodation groove 12g may be formed into a cylindrical shape,
and the center axis of the inner bottom face b is made to be
parallel with the opposed face 12a of the holding plate 12. As
a result, when the connecting cartridge is accommodated in the
accommodation groove 12g, the center axis of the connecting
cartridge (center axis of the radiation source S) and the center
axis of the inner bottom face b are parallel with each other,
so that it is possible to make the center axes of the multiple
radiation sources S held by the connecting cartridge into
parallel with the opposed face 12a of the holding plate 12. In
addition, by forming the cylindrical shape of the inner bottom
face b of the accommodation groove 12g and its radius of
curvature to have the same length as the radius of the outer
diameter of the connecting cartridge, the connecting cartridge
will not rattle in the accommodation groove 12g, with the result
that it is possible to measure the radiation intensity of the
multiple radiation sources S accurately.
[0144]
When the shapes of the holding plates 12B, 12C for
accommodating the rectangular cartridge C2 and the shaft-shaped
cartridge C3, or the shape of the holding plate for
accommodating the cartridge of other shape are made to be
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CA 02886802 2015-03-30
,
substantially equal to the shape of the aforementioned holding
plate (the holding plate 12 for accommodating the container PK) ,
it is possible to change the cartridge to be measured only by
replacing the holding plate. That is, by preparing holding
plates having different shapes of accommodation groove, it is
possible to deal with multiple cartridges by one apparatus.
[0145]
The holding plates 12B, 12C for accommodating the
rectangular cartridge C2 and the shaft-shaped cartridge C3, and
the holding plate for accommodating the cartridge of other shape
are not limited to those accommodating multiple of the
rectangular cartridges C2 or the like, but may be those
accommodating only one rectangular cartridge C2 or the like.
That is, it may have only one accommodation groove 12g. Also
in this case, likewise the case where the holding plate 12 holds
only one container PK as described above, it is possible to make
the holding plate 12 compact, so that a merit of downsizing the
apparatus is obtained.
[0146]
(Regarding the configuration in which holding plate 12 is not
provided)
In the above description, the case where the holding means
has the holding plate 12 is described. However, a groove
having an equivalent structure as the accommodation groove 12g
of the holding plate 12 may be formed in the holding part llb
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CA 02886802 2015-03-30
. .
of the frame part 11 without providing the holding plate 12.
For example, the case where 15 radiation sources S are
accommodated in one cartridge C is considered. Since the number
of radiation sources S to be used for one patient is normally
about 50 to 150, it is possible to test every radiation source
S to be used for one patient at one measurement by providing
the grooves at ten positions. In the case of use in such a state,
it is possible to measure the radiation intensity rapidly for
every radiation source S required for the therapy without having
the structure that enables holding plate 12 to be attached or
detached to/from the holding part 11b. In this case, the plate
having the same structure as the holding plate 12 may be directly
fixed to the multiple leg parts ha to give the holding part
11b. As a result, even in the case of measuring the cartridge
C having a different shape (for example, the rectangular
cartridge C2 or the shaft-shaped cartridge C3) , it is possible
to measure the radiation intensity of the radiation source S
accommodated in the cartridge C having the different shape by
replacing the plate having the same structure as the holding
plate 12, and to facilitate the replacement of the plate.
INDUSTRIAL APPLICABILITY
[0147]
The radiation intensity measuring apparatus for small
sealed radiation sources for cancer therapy of the present
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invention is suited for measuring radiation intensity of small
sealed radiation sources for use in small sealed radiation
source therapy for prostate cancer.
DESCRIPTION OF REFERENCE SIGNS
[0148]
1 radiation intensity measuring apparatus
lh measurement space
holding part
11 frame part
12 holding plate
12a opposed face
12g accommodation groove
12s radiation emitting part
moving mechanism
radiation intensity measuring means
31 sensor
31a detecting part
shielding member
35h slit
calibration part
cartridge
SC seed cartridge
89
